Avatars don’t have a database entry. They live here:
/wp-content/uploads/avatars/[member_id]/[avatar file]
But there needs to be a thumb and a full-size, and you’ll need to change the file names.
And they may need to be jpg.
For example:
4f5664228829d-bpthumb.jpg
4f5664228829dauto-bpfull.jpg